Stanislav Böhm

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We prove that language equivalence of deterministic one-counter automata is NL-complete. This improves the superpolynomial time complexity upper bound shown by Valiant and Paterson in 1975. Our main contribution is to prove that two deterministic one-counter automata are inequivalent if and only if they can be distinguished by a word of length polynomial in(More)
The main goal of this paper is to introduce the tool Kaira that we are developing. This tool is intended for modelling, simulation and generation of parallel applications. A developer is able to model parallel programs and different aspects of communication using Kaira. The used model is based on the variant of Coloured Petri Nets. Coloured Petri Nets(More)
A one-counter automaton is a pushdown automaton with a singleton stack alphabet, where stack emptiness can be tested; it is a real-time automaton if it contains no ε-transitions. We study the computational complexity of the problems of equivalence and regularity (i.e. semantic finiteness) on real-time one-counter automata. The first main result shows(More)
Structure of protonated nitro compounds was investigated by calculations at the levels MP2(FC)/6-311++G(2d,2p)//MP2(FC)/6-311++G(2d,2p)(nitromethane and reference compounds) or B3LYP/6-311+G(d,p)//B3LYP/6-311+G(d,p)(nitrobenzene and its 18 meta- and para-substituted derivatives). The group NO2H+ reveals many similarities with the isoelectronic group CO2H as(More)
We prove that deciding language equivalence of deterministic realtime one-counter automata is NL-complete, in stark contrast to the inclusion problem which is known to be undecidable. This yields a subclass of deterministic pushdown automata for which the precise complexity of the equivalence problem can be determined. Moreover, we show that deciding(More)
The structures of ortho-substituted benzoic acids with substituents bearing hydrogen atoms (OH, NH2, COOH and SO2NH2) were investigated by means of IR spectroscopy and of density functional theory at the B3LYP/6-311 + G(d,p) level. All possible conformations, hydrogen bonds, tautomeric forms and zwitterions were taken into consideration and particular(More)
Our research is focused on the simplification of parallel programming for distributed memory systems. Our overall goal is to build a unifying framework for creating, debugging, profiling and verifying parallel applications. The key aspect is a visual model inspired by Colored Petri Nets. In this paper, we will present how to use the visual model for(More)
Parallel computing can be very useful for meta-heuristic algorithms, because it can reduce time to find a solution with given properties. On the other hand parallel programming is generally more difficult than the sequential one and we need more development time to get a working parallel solution. We are developing a tool named Kaira which is intended for(More)